Not too long ago Apple released a new build of Mac OS X 10.5, Leopard, to select testers. AeroXP now has some screenshots of this new build. They report, for one thing, that even though it is available, ZFS is not actually working in this build. Update: ThinkSecret has more screenshots and an overview.

"The very first backup is a full copy. All subsequent backups contain hard links to the unchanged portions of the previous backup."

I figured it was something like that. Nothing particularly amazing, but if it works well, great. Not enough people back up properly (including myself, hahaha.) Plus they have the typically cool Apple UI on it.